Insulated Glazing Units (IGUs) are used to reduce thermal loss through architectural exterior wall windows. A typical IGU includes two panes, a spacer frame, and a cavity formed by these three elements. Microoptical elements integrated into an IGU can be used to redirect some of the sunlight passing through the IGU to an interior ceiling, to augment conventional interior lighting, thereby increasing the energy efficiency of buildings. In many cases, it can be convenient to integrate the microoptical elements directly on the glass of the window, e.g., by applying refractive or diffractive optical structures to the surface of the glass such as within the cavity of an IGU such as described in US2014/0021492 and US2014/0178646; incorporated herein by reference.